a-a a-c aaa aac aaf aao aap aar aas ac- aca acc acf aco acp acr acs af- afa afc aff afo afp afr afs aoa aoc aof aoo aop aor aos ap- apa apc apf apo app apr aps ar- ara arc arf aro arp arr ars as- asa asc asf aso asp asr ass c-- caa cac caf cao cap car cas cca ccc ccf cco ccp ccr ccs cfa cfc cff cfo cfp cfr cfs co- coa coc cof coo cop cor cos cpa cpc cpf cpo cpp cpr cps cra crc crf cro crp crr crs csa csc csf cso csp csr css faa fac faf fao fap far fas fca fcc fcf fco fcp fcr fcs ffa ffc fff ffo ffp ffr ffs foa foc fof foo fop for fos fpa fpc fpo fpp fpr fps fra frc frf fro frp frr frs fsa fsc fsf fso fsp fsr fss oaa oac oaf oao oap oar oas oc- oca occ ocf oco ocp ocr ocs of- ofa ofc off ofo ofp ofr ofs oo- ooa ooc oof ooo oop oor oos op- opa opc opf opo opp opr ops or- ora orc orf oro orp orr ors os- osa osc osf oso osp osr oss p-p paa pac paf pao pap par pas pca pcc pcf pco pcp pcr pcs pfa pfc pff pfo pfp pfr pfs poa poc pof poo pop por pos ppa ppc ppf ppo ppp ppr pps pra prc prf pro prp prr prs ps- psa psc psf pso psp psr pss ra- raa rac raf rao rap rar ras rca rcc rcf rco rcp rcr rcs rfa rfc rff rfo rfp rfr rfs roa roc rof roo rop ror ros rpa rpc rpf rpo rpp rpr rps rra rrc rrf rrp rrr rrs rsa rsc rsf rso rsp rsr rss saa sac saf sao sap sar sas sca scc scf sco scp scr scs sfa sfc sff sfo sfp sfr sfs soa soc sof soo sop sor sos spa spc spf spo spp spr sps sr- sra src srf sro srp srr srs ss- ssa ssc ssf sso ssp ssr sss